How to make effect of burning objects from Particles?
I dont think there is an easy solution in the direction your heading.
And probaply no easy solutions exists.
But know that Blender understands Python, and with that it should be possible.
If you know the locations of the object replace them, or better use shape keys on them to shrink them. Then be able to move a texture over the object so it turns black from top to bottom. Doing this with python might not be easy, though all actions you do are logged inside
Maybe animation nodes could allow something like this (but i'm not sure).
Generating trees with leaves is one of the goals though.